% Documentation for Astrographic Catalogue Reference Stars % (Corbin and Urban 1991) % % Document Number: NSSDC/WDC-A-R&S 91-10 % % Written: April 1991 by Corbin, Urban, and Warren % TeX Ver: June 1991 by Lee E. Brotzman % \documentstyle [adc,11pt]{article} % \newcommand{\dmv}{Documentation for the Machine-Readable Version of the} \newcommand{\cat}{Astrographic Catalogue Reference Stars} \newcommand{\abbr}{1171} \newcommand{\prefp}{Corbin and Urban 1991} \newcommand{\adc}{Astronomical Data Center} \newcommand{\docnum}{NSSDC/WDC-A-R\&S 91-10} % \begin{document} % \setcounter{page}{0} \thispagestyle{empty} \null \vfil \vskip 1in \begin{center} \begin{tabular}{c} {\LARGE \cat} \\ \\ {\Large (\prefp)} \\ \\ Documentation for the Computer-Readable Version \\ \\ {\small Thomas E. Corbin and Sean E. Urban} \\ {\small U.~S. Naval Observatory} \\ \\ {\small Wayne H. Warren Jr.} \\ {\small National Space Science Data Center} \\ \\ {\small April 1991} \\ \\ {\small Doc. No. \docnum} \\ \\ \\ {\small National Space Science Data Center (NSSDC)/} \\ {\small World Data Center A for Rockets and Satellites (WDC-A-R\&S)} \\ {\small National Aeronautics and Space Administration} \\ {\small Goddard Space Flight Center} \\ {\small Greenbelt, MD 20771} \end{tabular} \end{center} \vfil \null \pagebreak \begin{abstract} The machine-readable version of the catalog, as it is currently being distributed from the \adc , is described. The ACRS is an all-sky catalog of positions and proper motions that is based on the AGK3 in the northern hemisphere and on the newly completed CPC2 in the south. The data of the ACRS are on the system of the {\em International Reference Stars} (IRS), compiled on B1950.0 FK4 and then transformed to J2000.0 FK5. The reductions and computations were done at the U.~S. Naval Observatory. \end{abstract} \section{Introduction} \subsection{Description} For a number of years there has been a great demand for a high-density catalog of accurate stellar positions and proper motions that maintains a consistent system of reference over the entire sky. The {\em Smithsonian Astrophysical Observatory Star Catalog} (SAO; SAO Staff 1966) has partially met those requirements, but its positions brought to current epochs now contain errors on the order of 1 second of arc, plus the proper motions in the SAO differ systematically with one another depending on their source catalogs. With the completion of the {\em Second Cape Photographic Catalogue} (CPC2; de Vegt {\em et al.} 1989), a photographic survey comparable in density to the AGK3 (Dieckvoss 1975) was finally available for the southern hemisphere. These two catalogs were used as a base and matched against the AGK2 (Schorr \& Kohlsch\"{u}tter 1951-58), Yale photographic zones (Yale Trans., Vols. 11-32), {\em First Cape Photographic Catalogue} (CPC1; Jackson \& Stoy 1954, 55, 58; Stoy 1966), {\em Sydney Southern Star Catalogue} (King \& Lomb 1983), Sydney Zone Catalogue $-48^{\circ}$ to $-54^{\circ}$ (Eichhorn {\em et al.} 1983), 124 meridian circle catalogs, and catalogs of recent epochs, such as the Carlsberg Meridian Catalogue, La Palma (CAMC), USNO Zodiacal Zone Catalog (Douglass \& Harrington 1990), and the Perth 83 Catalogue (Harwood [1990]) to obtain as many input positions as possible. All positions were then reduced to the system of the FK4 (Fricke \& Kopff 1963) using a combination of the FK4, the FK4 Supplement as improved by H. Schwan of the Astronomisches Rechen-Institut in Heidelberg, and the {\em International Reference Stars} (IRS; Corbin 1991), then combined with the CPC2 and AGK3. The total number of input positions from which the ACRS was formed is 1,643,783. The catalog is divided into two parts. Part 1 contains the stars having better observational histories and, therefore, more reliable positions and proper motions. This part constitutes 78 percent of the catalog; the mean errors of the proper motions are $\pm0\secdot47$ per century and $\pm0\secdot46$ per century in right ascension and declination, respectively. The stars in Part 2 have poor observational histories and consist mostly of objects for which only two catalog positions in one or both coordinates were available for computing the proper motions. Where accuracy is the primary consideration, only the stars in Part 1 should be used, while if the highest possible density is desired, the two parts should be combined. The ACRS was compiled at the U.~S. Naval Observatory with the intention that it be used for new reductions of the {\em Astrographic Catalogue} (AC) plates. These plates are small in area ($2^{\circ} \times 2^{\circ}$) and the IRS is not dense enough. Whereas the ACRS was compiled using the same techniques developed to produce the IRS, it became clear as the work progressed that the ACRS would have applications far beyond its original purpose. With accurate positions and proper motions rigorously reduced to both the FK4 and FK5 (Fricke {\em et al.} 1988) systems, it does more than simply replace the SAO. Rather, it provides the uniform system of reference stars that has been needed for many years by those who require densities greater than the IRS and with high accuracy over a wide range of epochs. It is intended that, as additional observations become available, stars will be migrated from Part 2 to Part 1, with the hope that eventually the ACRS will be complete in one part. Additional details concerning the compilation and properties of the ACRS can be found in Corbin \& Urban (1989) except that the star counts and errors given here supersede the ones given in 1989. This document describes the machine-readable version of the {\em \cat} compilation as it is currently being distributed from the international network of astronomical data centers. It is intended to enable users to read and process the data without problems and guesswork. {\bf A copy of this document should be transmitted to any recipient of the machine-readable catalog originating directly from the data centers.} \subsection{Source Reference} \begin{references} \item Corbin, T. E., \& Urban, S. E. 1991, \cat\ (Washington, U.~S. Naval Observatory) \end{references} \section{Structure} \subsection{File Summary} \label{s:FS} The machine version of the ACRS consists of two files. Table \ref{t:sumtab} gives the machine-independent file attributes. All logical records are of fixed length, and, if the catalog is received on magnetic tape, it will contain blocks of fixed length, except that the last block of each file may be short. \begin{table}[htbp] \centering \begin{tabular}{|c|l|c|c|r|} \hline \multicolumn{5}{|c|}{\cat} \\ \multicolumn{5}{|c|}{(\prefp)} \\ \hline & & Record & Record & \multicolumn{1}{c|}{Number of} \\ File & \multicolumn{1}{c|}{Contents} & Format & Length & \multicolumn{1}{c|}{Records} \\ \hline 1 & Catalog Part 1 & Fixed & 192 & 250052 \\ 2 & Catalog Part 2 & Fixed & 192 & 70159 \\ \hline \end{tabular} \caption{Summary Description of Catalog File} \label{t:sumtab} \end{table} The information contained in the above table is sufficient for a user to describe the indigenous characteristics of the machine-readable version of the {\em \cat} to a computer. Information easily varied from installation to installation, such as block size (physical record length), blocking factor (number of logical records per physical record), total number of blocks, density, number of tracks and character coding (ASCII, EBCDIC) for tapes, is not included, but should always accompany secondary copies if any are supplied to other users or installations. \subsection{Catalog (Files 1 and 2 of 2)} \label{s:cathdc} As mentioned in the introduction, the ACRS is divided into two parts. Since both parts are identically formatted, the byte-by-byte description given in Table 2 applies to both. The data files are ordered by J2000.0 right ascension. Table \ref{t:cattab} gives a byte-by-byte description of the contents of the data files. A suggested Fortran format specification for reading each data field is included and can be modified depending upon individual programming and processing requirements (Fortran 77 character string-type formats are used throughout). Only the spectral-type and IAU-recommended ACRS identifier fields contain character data, for which the default value (former field only) is always a blank field. Note that all numerical data in the catalog are recorded as integers; however, the format specifications given are intended to read the data as real numbers with the correct units as given in the table. \begin{table}[htbp] \centering \begin{tabular}{|c|c|c|c|l|} \hline & & Suggested & Default & \\ Bytes & Units & Format & Value & \multicolumn{1}{c|}{Data} \\ \hline 1 & --- & I1 & --- & Catalog part \\ 2-7 & --- & I6 & --- & ACRS number \\ 8 & --- & 1X & --- & Zero \\ 9-10 & h & I2 & --- & Right ascension, $\alpha$, B1950.0 \\ 11-12 & min & I2 & --- & $\alpha$ \\ 13-17 & s & F5.3 & --- & $\alpha$ \\ 18-20 & deg & I3 & --- & Declination, $\delta$, B1950.0 \\ 21-22 & arcmin & I2 & --- & $\delta$ \\ 23-26 & arcsec & F4.2 & --- & $\delta$ \\ 27-29 & s & F3.3 & blank & Mean error in $\alpha$ (at original epoch) \\ 30-32 & arcsec & F3.2 & blank & Mean error in $\delta$ (at original epoch) \\ 33-38 & s & F6.3 & --- & Centennial proper motion, $\mu_{\alpha}$, B1950.0 \\ 39-45 & arcsec & F7.2 & --- & Centennial proper motion, $\mu_{\delta}$, B1950.0 \\ 46-49 & s/cy & F4.3 & blank & Mean error in $\mu_{\alpha}$ \\ 51-53 & arcsec/cy & F4.2 & blank & Mean error in $\mu_{\delta}$ \\ 54-60 & years & F7.3 & --- & Original epoch of $\alpha$ and $\mu_{\alpha}$ \\ 61-67 & years & F7.3 & --- & Original epoch of $\delta$ and $\mu_{\delta}$ \\ 68-70 & --- & I3 & --- & Number of positions in $\alpha$ \\ 71-73 & --- & I3 & --- & Number of positions in $\delta$ \\ 74-77 & --- & F4.1 & --- & Weight in $\alpha$ \\ 78-81 & --- & F4.1 & --- & Weight in $\delta$ \\ 82-86 & mag & F5.2 & 99.9 & Magnitude \\ 87-89 & --- & A3 & --- & Spectral type \\ 90-97 & --- & A8 & --- & BD number \\ 98-105 & --- & A8 & --- & CD number \\ 106-113 & --- & A8 & --- & CPD number \\ 114-120 & --- & A7 & --- & AGK3 number \\ 121-126 & --- & A6 & --- & CPC2 number \\ 127-150 & --- & A24 & --- & ACRS identifier \\ 151-152 & h & I2 & --- & Right ascension, $\alpha$, J2000.0 \\ 153-154 & min & I2 & --- & $\alpha$ \\ 155-159 & s & F5.3 & --- & $\alpha$ \\ 160-165 & s & F6.3 & --- & Centennial proper motion, $\mu_{\alpha}$, J2000.0 \\ 166-171 & Jcy & F6.5 & --- & Original epoch - J2000.0 in $\alpha$ \\ 172-174 & deg & I3 & --- & Declination, $\delta$, J2000.0 \\ 175-176 & arcmin & I2 & --- & $\delta$ \\ 177-180 & arcsec & F4.2 & --- & $\delta$ \\ 181-186 & arcsec & F6.2 & --- & Centennial proper motion, $\mu_{\delta}$, J2000.0 \\ 187-192 & Jcy & F6.5 & --- & Original epoch - J2000.0 in $\delta$ \\ \hline \end{tabular} \caption{Data File Record Format} \label{t:cattab} \end{table} \begin{definition}{24ex} \item[Catalog part] The part is specifically identified as 1 or 2 so that if the parts are merged, the source remains easily recognizable. \item[ACRS number] A sequential number beginning with 1 for Part 1 and with 500001 for Part 2. These numbers will not remain ordered as stars migrate from Part 2 to Part 1. \item[Equatorial coordinates] Positions are given for equinox and epoch B1950.0 on the system of FK4 (bytes 9-26). They are also given for equinox and epoch J2000.0 on the system of FK5 (bytes 151-159 and 172-180) after transformation of the B1950.0 values. The transformation was done using the coefficients and software package of Schwan (see Schwan 1988) and the algorithm given in the 1991 {\em Astronomical Almanac} (page B42) (foreshortening terms set to zero). (See Section 3.1 for additional details.) \item[Proper motions] Referred to B1950.0 on FK4 (bytes 33-45) and to J2000.0 on FK5 (bytes 160-165 and 181-186). \item[Mean errors] The mean errors of the positions refer to the original epochs given in bytes 54-67. The proper-motion errors were derived in each case from the dispersion of the catalog positions used to determine the proper motion. \item[Original epochs] Each refers to the mean epoch of the mean position from the respective proper-motion solution. \item[Number of positions] The number of positions used to determine the proper motion and mean position in each coordinate. \item[Weights] The sum of the weights of the catalogs used in each coordinate. \item[Magnitude] Magnitudes are photographic and come from the AGK3 in the north and the CPC2 in the south. \item[Spectral type] Spectral type from the AGK3 (north only). No spectral types are given for the southern stars. \item[DM numbers] Identifier from one of the Durchmusterung (DM) catalogs, identified as one of the following: \begin{definition}{5ex} \item[BD] {\em Bonner Durchmusterung} (Argelander 1859-62, K\"{u}stner 1903, Sch\"{o}nfeld 1886) \item[CD] {\em C\'{o}rdoba Durchmusterung} (Thome 1892-1932) \item[CPD] {\em Cape Photographic Durchmusterung} (Gill \& Kapteyn 1895-1900). \end{definition} \item[AGK3 number] Identifier from the AGK3 catalog (Dieckvoss 1975). \item[CPC2 number] Identifier from the {\em Second Cape Photographic Catalogue} (de Vegt {\em et al.} 1989). \item[ACRS identifier] An identifier for each star based upon the recommended IAU nomenclature (see PASP, 102, 1444, 1990). The field consists of an {\em origin} in bytes 127-130 (ACRS) and a coordinate specification in bytes 132-150 (byte 132 contains a ``J'' to indicate that the following coordinates are in the Julian reference system and are for the year 2000.0, the standard equinox designated for Julian system coordinates). \end{definition} \section{History} \label{s:history} \subsection{Remarks} The ACRS positions and proper motions in the original catalog are given for the equinox and epoch of B1950.0 and are referred to the FK4 system. The reduction of these data to the new reference frame of the FK5 involves the application of transformation coefficients to the FK4 data, followed by another transformation from the equinox and epoch B1950.0 to the equinox and epoch J2000.0. The reduction of the B1950.0 FK4 data to the FK5 system was effected by using the coefficients of H. Schwan (Astronomisches Rechen-Institut, Heidelberg), communicated to us as part of a computer subroutine package (see Schwan 1988). The coefficients represent the systematic differences between the FK4 and FK5 catalog positions and proper motions for the mean equinox and epoch B1950.0; they are given in the system of the FK4 catalog. The arguments needed as input to the computer subroutines are the right ascension, declination, and magnitude. The subroutine returns systematic corrections to the FK4 positions and proper motions. In general, the magnitudes of the ACRS catalog stars lie outside the range of magnitudes of the stars in the FK4 catalog and are inappropriate to use as arguments because the magnitude-related error of the FK4 system is not defined outside the magnitude range of the FK4 stars. An average FK4 magnitude was estimated for each ACRS position from the average magnitude of all FK4 stars in an area on the celestial sphere bounded by a four-hour interval in right ascension and a $20^{\circ}$ interval in declination centered on the star. All stars less than $10^{\circ}$ from the pole were treated as if they had been at $80^{\circ}$ declination for the calculation of the average FK4 magnitude only. After the ACRS positions and proper motions had been referred to the FK5 system by using the procedure described above, they were transformed from the equinox B1950.0 basis to J2000.0 using the algorithm given in the 1991 volume of the {\em Astronomical Almanac} (page B42). The algorithm was applied with the foreshortening terms set to zero. By the use of that algorithm, elliptic terms in aberration are removed, the IAU 1976 precession is introduced, the FK4 equinox error in the right ascension position and proper-motion system is corrected, and the time scale for the proper motions is shifted from units of tropical centuries to Julian centuries of exactly 36525 days. The completed machine-readable ACRS was transferred to the \adc\ on magnetic tape and received there on 3 April 1991. \section{References} \begin{references} \item Argelander, F. W. A. 1859-62, Bonner Sternverzeichniss, erste bis dritte Sektion, Astronomischen Beobachtungen auf der Sternwarte der K\"{o}niglichen Rhein., Friedrich-Wilhelms-Universit\"{a}t zu Bonn, B\"{a}nde 3-5 \item Corbin, T. E. 1977, The Proper-Motion System of the AGK3R (Ann Arbor, University Microfilms, Inc.) \item Corbin, T. E. 1991, International Reference Stars (IRS) Catalog, (Washington, U.~S. Naval Observatory) \item Corbin, T. E., \& Urban, S. E. 1989, in Star Catalogues: A Centennial Tribute to A. N. Vyssotsky (Schenectady, L. Davis Press), p. 59 \item Corbin, T. E., \& Urban, S. E. 1990, in IAU Symposium No. 141, Inertial Coordinate System on the Sky, ed. J. H. Lieske \& V. K. Abalakin (Dordrecht, Reidel), p. 433 \item de Vegt, Ch., Zacharias, N., Murray, C. A., \& Penston, M. J. 1989, in Star Catalogues: A Centennial Tribute to A. N. Vyssotsky (Schenectady, L. Davis Press), p. 45 \item Dieckvoss, W. (in collaboration with H. Kox, A. G\"{u}nther, \& E. Brosterhus) 1975, AGK3 Star Catalogue of Positions and Proper Motions North of -2.5 Degrees Declination, Hamburg-Bergedorf (printed with financial support from Deutsche Forschungsgemeinschaft, Bonn-Bad Godesburg) \item Douglass, G. G., \& Harrington, R. S. 1990, AJ, 100, 1712 \item Eichhorn, H., Googe, W. D., Lukac, C. F., \& Murphy, J. K. 1983, AJ, 88, 546 \item Harwood, D. N. [1990], Perth 83, A Catalogue of Positions of 12,263 Stars (Perth, Perth Observatory) \item Fricke, W., \& Kopff, A. 1963, Fourth Fundamental Katalog (FK4), Ver\"{o}ff. Astron. Rechen-Inst. Heidelberg No. 10. \item Fricke, W., Schwan, H., \& Lederle, T. (in collaboration with Bastian, U., Bien, R., Burkhardt, G., du Mont, B., Hering, R., J\"{a}hrling, R., Jahreiss, H., R\"{o}ser, S., Schwerdtfeger, H. M., \& Walter, H. G.) 1988, Fifth Fundamental Catalogue (FK5), Part I. The Basic Fundamental Stars, Ver\"{o}ff. Astron. Rechen-Institut Heidelberg No. 32 \item Gill, D. \& Kapteyn, J. C. 1895-1900, Cape Photographic Durchmusterung, Ann. Cape Obs., 3 (1895, Part I: zones $-18^{\circ}$ to $-37^{\circ}$); 4 (1897, Part II: zones $-38^{\circ}$ to $-52^{\circ}$); 5 (1900, Part III: zones $-53^{\circ}$ to $-89^{\circ}$) \item Jackson, E. S., \& Stoy, R. H. 1954-1958, Ann. Cape Obs., 17-20 \item King, D. S., \& Lomb, N. R. 1983, J. Proc. R. Soc. N.S.W., 116, 53 (Sydney Obs. Paper No. 96) \item K\"{u}stner, F. 1903, Bonner Durchmusterung des N\"{o}rdlichen Himmels, zweite berichtigte Auflage, Bonn Universit\"{a}ts Sternwarte (Bonn, A. Marcus und E. Weber's Verlag) \item Sch\"{o}nfeld, E. 1886, Bonner Sternverzeichniss, vierte Sektion, Astronomische Beobachtungen auf der Sternwarte der K\"{o}niglichen Rheinischen Friedrich-Wilhelms-Universit\"{a}t zu Bonn, 8, Part IV (Bonn, Adolph Marcus) \item Schorr, R., \& Kohlsch\"{u}tter, A. 1951-1958, Zweiter Katalog der Astronomischen Gesellschaft f\"{u}r das \"{A}quinoktium 1950, 1-10 (Hamburg-Bergedorf), 11-15 (Bonn, Ferd. D\"{u}mmlers Verlag) \item Schwan, H. 1988, A\&A, 198, 363 \item Stoy, R. H. 1966, Ann. Cape Obs., 21-22 \item Thome, J. M. 1892-1932, C\'{o}rdoba Durchmusterung, Resultados del Observatorio Nacional Argentino, 16 (1892, Part I: $-22^{\circ}$ to $-32^{\circ}$); 17 (1894, Part II: $-32^{\circ}$ to $-42^{\circ}$); 18 (1900, Part III: $-42^{\circ}$ to $-52^{\circ}$); 21 (Part I) (1914, Part IV, $-52^{\circ}$ to $-62^{\circ}$); 21 (Part II) (1932, Part V: $-62^{\circ}$ to $-90^{\circ}$) \end{references} \end{document}